Two-cycle internal combustion engine



c. e. CURTIS ET AL 1,855,791 TWO-CYCLE INTERNAL COMBUSTION ENGINE April 26, 1932.

Filed July 29, 1929 2 Sheets-Sheet 1 L J2 T 1 4 HARLEEEFQUEWIS NEWTON a? R ORNEY A ril 26, 1932. c. G. cuRTls ET AL 1,855,791

TWO-CYCLE INTERNAL COMBUSTION ENGINE Filed July 29, 1929 2 Sheets-Sheet 2 Patented Apr. 26, 1932 UNITED STATES PATENT OFFICE CHARLES Gr. CURTIS, OF NEW YORK, AND R. lil'EWTON, F J'A'MAICA, NEW YORK TWO-CYCLE INTERNAL COMBUSTION ENGINE Application filed July 29,

V This invention relates to the scavenging of two-cycle engines and it main object is to provide a means of scavenging the engine cylinder which will have a high efficiency and E which at the same time will cause a turbulence in the air column so as to secure efficient combustion of the fuel.

Several embodiments of the invention are illustrated in the accompanying drawings, in which Fig. 1 is a vertical sectional view of an engine cylinder having exhaust ports on one side and two sets of inlet ports on the other side.

Fig. 2 is a horizontal sectional through the broken plane ab Fig. 1.

Fig. 3 is a similar view through the plane ac Fig. 1.

Fig. 4 is a vertical sectional view similar to Fig. 1 showing a modified arrangement of the inlet ports.

Fig. 5 is a vertical sectional view similar to Fig. 1 incorporating means for providing a supercharge in the cylinder. Fig. 6 is a vertical sectional view of a double-acting Diesel engine cylinder embodying the present invention.- I Fig. 7 is a view similar to Fig. 6 incorporating means for providing a supercharge in the cylinder of a double-acting engine, and Fig. 8 is a horizontal sectional view on the line 03, 6, Fig. 6, the structure being slightly modified however, the middle inlet port being omitted. Figs 9, l0 and 11 are all detail Views In vertical section through ports 34, 32' and respectively, to illustrate the different angularity of the ports in different parts of the. bank 16.

view

0 Referring to said drawings, numeral 10' designates a cylinder of a two-cycle internal combustion engine, (1010 in the double acting embodiments), 12 a reciprocating pisare preferably arranged at one side of the cylinder wall, in position to be opened and 9 closedloy the piston 12 (or 12 and may have 1929. Serial N0. 381,736.

the usual form of radial exhaust ports, or any other suitable form.

The cylinder 10 is alsoprovided with two banks of inlet ports 16 and 18, which arepreferably arranged one bank above the other,

and also preferably arranged in the side of the cylinder wall opposite the bank of exhaust ports 14, and in position to'be opened and closed by the piston 12 (or 12 The bank of inlet ports'16 may be constructed and arranged according to the invention disclosed and claimed in Curtis U. S. Patent No. 1,777,827 dated October 7, 1930 and in our Patent #1,? 80,17 5. dated November 4, 1930, and in our co-pending application a in the bank, according to said arrangement, 7

as for example the ports 30, 31, 32, 33, 30*, 31, 32 33, are arranged to direct their streams back toward the side of the cylinder containing the bank 16, (Fig. 8) and are progressively less oblique vertically or at less inclinationthan the middle port or ports (see for example'port 32, Fig. 10), the ports in the end portions being preferably horizontal or approximately horizontal (see for example port 30, Fig. 11). v

The ports of the bank 16 may however be made of considerably less depth (or height) than accords with common practice.

By the arrangement described herein (according to our aforesaid application Serial No. 37 5,928 and others mentioned) the air streams issuing from the ports are directed so as to produce a column tending to flow longitudinally of the cylinder on that side of the cylinder at which the bank 16 is located. These ports are shown as being directed toward a common center within the cylinder, and in order to get as much area as possible the ports in the end portions of the bank 16 are, assuming the cylinder to be vertical, made horizontal (or nearly horizontal) as heretofore described, while the middle porttially at an angle sufficient to give a substan-.

tial rotary motion to the air, and preferably point upward, as for example at an angle of 45 as shown in Figs. 1, 4, 5, 6 and 7.

The upper row of ports (those in bank 18 as here shown) may extend above' the top of the exhaust ports 14, and when so arranged may serve for supercharging, as illustrated in Figs. 5, 6 and 7.

The bank of inlet ports 16 may be in communication, as illustrated in Figs. 3 and 8 with the usual air belt 36. Similarly the bank of inlet ports 18 may be in communication with an air belt 38 as shown inFig. 2, and the bank of exhaust ports 14 may also be connected with the usual exhaust belt 40, Figs. 2, 3 and 8. e

The air belt 38 communicating with the ports in bank 18 may be separate from the belt 36 communicating with the ports in bank 16. The belts 36 and 38 may however be in communication through a passage 42, both belts thereby being supplied with air through a pipe 44 from any suitable source.

Means are provided for preventing the flow of gas from the cylinder 10 through the upper bank of ports to the air supply, during the time on the exhaust stroke of the piston that the pressure inthe cylinder is above the pressureof the air supply in pipe 44. This is conveniently effected in the embodiments shown, by providing an automatic valve (or valves) 46 opening inwardly into the belt 38, which opens and closes according to the difference in pressure on its upper and lower surfaces. On the down stroke of the piston 12 the ports in the upper bank 18 are disclosed first, but the pressure on the top of the valve 46 is such that it remains closed and there is no How through-passage 42 in either direction, except that some of the gas in the cylinder 12 flows into and fills the belt 38 between the valve 46 and the cylinder according to the usual practice when two rows of ports are used. As the piston 12 descends further the exhaust ports 14 are opened, and

after the exhaust ports 14 have been opened sufliciently to drop the cylinder pressure to a point below the air supply pressure the automatic valve 46 opens and the piston uncovers the inlet ports in the lower bank 16 permitting the scavenging air to flow in through the ports of both banks 16 and 18. The scavening air admitted into the cylinder 10 through the ports of the upper bank 18 gives more ,or less of a rotary action to the air and under these conditions ports in the upper and lower banks 18 and 16 cooperate effectively to produce good scavenging and the desired turbulence. As the piston 12 rises on the return stroke it first cuts ofi the inlet ports in the lower bank 16 but the air continues to flow through the ports in the upper bank 18; and even after thepiston 12 has reached the top of the exhaust ports 14 where the ports in the bank 18 extend above t 1e exhaust ports) the air may still continue to flow in through the ports in the bank 18 maintaining the turbulence and supercharging the cylinder to a greater or lesser degree according to the scavening air pressure used. The ports in the upper bank 18 thus give a substantial rotary motion to the air; first in combination with the ports in the lower bank 16 and subsequently by themselves, so that by the time the compression has begun there is a substantial rotary motion to the air which will continue during compression and will assist substantially in burning the fuel rapidly. The ports-in the upper bank 18- may extend more or less above the exhaust ports 14 so as to give a supercharging effect if desired.

By locating the top of the inlet ports in the upper bank flush with the top of the exhaust ports similar to the ports 14 and 18 shown in Fig. 4, an equal or possibly greater amount of air or charge can be introduced into the cylinder 10, because while the pressure resulting in the cylinder at the moment the ports close will be less, the point where compression begins will be lower down and the compression stroke is increased, so that the net result so far as power is concerned is as good or better than in the case where the tops 0t said ports in bank 18 are above the exhaust ports, as shown in Fig. 1.

It may be desirable to feed the cylinder 10 with a supercharge, that is, with acharge of air which is higher than the scavenging air. We have shown a means of doing this .in-Fig. 5. The upper air-belt 38 is fed from two sources: (1) from the lower scavenging air belt 36 with air at say 1 or 2 lb. pressure admitted through the automatic valve 46; (2) from a chamber 50 recei ving air at a higher pressure say at 5 lb. pressure, through an automatic, cam-operated time valve 52. On the down stroke of the piston 12. after the pressure in the cylinder 10 has dropped to a pressure below the scavenging air supply pressure by the opening of the exhaust ports 14.air flows through the automatic valve 46 and through ports in both banks 16 and 18 at the ordinary scavenging pressure. On the return stroke of the piston 12 and preferably before the piston has reached the top of the exhaust ports 14 the cam operated time valve 52 begins to open and before the exhaust ports 14 are closed this valve has opened wide so as to admit 5 lb. air to the inlet ports in the upperbank 18 (due to the increased pressure) giving an increased rotary motion to the column of air at the last minute, bringing the pressure in the cylinder 10 up nearly to 5 lb. pressure so as to furnish a substantial supercharge. In this way a high scavenging efficiency can be obtained, a very substantial supercharge can be had and the air is given a more violent turbulence or rotary, motion at the last moment. If it is desired to operate with no greater supercharge than can be obtained with ordinary scavenging air then a mechanically operated valve 54 provided between chamber and a duct 56 leading the 5 lb. air thereto, is kept closed and the only air supplied to the inlet ports in the upper bank 18 is that coming through the automatic valve 46.

An embodiment of a double acting engine provided with three banks of inlet portsand operating in a manner similar to the singleacting embodiment illustrated in Figs. 1-8 inclusive is illustrated in Fig. 6. In said embodiment the cylinder l0-10 is provided with a bank of inlet ports 18 corresponding to the bank 18, and the two banks 18 and 18 of inlet ports may be and preferably are symmetrically arranged with relation to the bank of inlet ports 16, and also with relation to the exhaust ports 14, which latter are lengthened to provide the same action of opening and closing of the ports at both ends of the stroke ofpiston 12 as is obtained in said single acting embodiment of Figs. 1-3. In the embodiment shown in Fig. 6, the position of the piston at one end of the stroke is illustrated in full lines'and at the other end is shown in dotted lines. An air belt 38 and an automatic valve 42' similar to the parts 38 and 42 may be provided in connection with said bank of inlet ports 18.

An embodiment of a double acting engine provided with three banks of inlet ports and operating similar to the single acting embodiment illustrated in Fig. 5, is illustrated in Fig. 7. The bank of inlet ports 18 is arranged the same as in Fig. 6. Likewise a belt 68 and an automatic valve 46 similar to the parts 38 and 46 is provided in connection with said bankof inlet ports 18. A

chamber 50 supplied from duct 56 with connection with Fig. 5. The exhaust ports 14 may also be lengthenedas described in reference to Fig. 6. The positions of the piston 12 at the ends of the two exhaust strokes are the same as described to Fig.

In the double acting embodiments of engines illustrated inv Figs. 6 and 7 we have shown a common middle bank 16 of inlet ports serving both the top and bottom side of the cylinderlO, 10 alternately and we may make all the ports in this bank 16 horizontal. In making the middle bank 16 of ports all horizontal it would be desirable to leave out as shown in Fig. 8 the radial middle port of the bank 16 because the middle port of the bank 16 is radial and if horizontal it gives a strong velocity component resultant directed across the cylinder toward the exhaust ports 14 resulting in a lowered scavenging efficiency.

The invention may receive'various other embodiments than those herein specifically illustrated and described.

l/Vhat is claimed is 1. A two cycle internal combustion engine comprising a cylinder, exhaust ports, scavenging air inlet ports comprising oppositely disposed ports turned back toward the inlet side of the cylinder in combination with additional air inlet ports arranged somewhat tangential to the cylinder and commonly directed so as to cause the air to rotate during compression.

2. A two cycle internal combustion engine above in reference comprising a cylinder, exhaust ports, scavenging air inlet ports comprising a centrally located oblique port directed toward the cylinder cover and oppositely disposed end ports arranged more nearly horizontal and turned back toward the inlet side of the cylinder in combination with additional commonly directed and somewhat tangential air inlet portsv which cause the air to rotate during compression.

3. A two cycle internal combustion engine comprising a cylinder, scavenging air inlet ports, one of which is centrally located and oblique to the longitudinal axis of the cylinder and directed toward the cylinder cover and others arranged on either sidev thereof less steeply oblique and turned back toward the inlet side of the cylinder and directed beneath the said centrally located port in combination with additional commonly directed and somewhat tangential air inlet ports which cause the air to rotate during compression.

4. A two cycle internal combustion engine according to claim 1, in which said additional air inlet ports are arranged in the same side of the cylinder wall as said scavenging air ports and nearer the cylinder cover end of the cylinder.

5. A two cycle internal combustion engine comprising a cylinder, exhaust ports,

scavenging air inlet ports comprising oppositely disposed ports turned back toward the inlet side of the cylinder I in combination with additional commonly directed somewhat tangential air inlet ports which cause the air to rotate during compression, and means whereby said additional ports are kept open after said exhaust ports are closed to admitof the cylinder receiving a supercharge.

6. A double-acting two cycle internal combustion engine comprising a cylinder, three grou s of air inlet ports, the ports of the middle group supplying scavengin air a1- ternately to the inner and outer en s of the cylinder, oppositely disposed ports in 'this middle group directed back toward the inlet side of the cylinder wall, the ports in each of the other two groups being commonly directed and somewhat tangential to the cylinder.

7. An engine according to claim 1, in which the said additional ports are located above the said scavenging air ports and the overall height of these two groups of ports is substantially the same as the height of the ex haust ports.

In witness whereof, we have hereunto signed our names.

CHARLES G. CURTIS. EARLE R. NEWTON. 

